1. Field of the Invention
This invention relates to a unique method and system for optimizing deployment of an occupant restraint system. The occupant restraint system includes a plurality of sensors that provide multiple input signals to a processing unit that has a fuzzy logic control system for processing the multiple input signals to generate multiple output signals that optimize deployment of the occupant restraint system.
2. Related Art
Many vehicles have airbag systems and seat belt mechanisms that are used to restrain occupants within a vehicle under certain deceleration requirements. If the vehicle decelerates suddenly, such as when a collision occurs, occupants will tend to continue to move forward due to inertial effects. An airbag is deployed under these circumstances to decelerate the occupants"" impact speed before they contact a vehicle structure, such as a steering wheel or dashboard. Additionally, if the occupant is wearing a seat belt, pretensioner and retractor mechanisms also assist in controlling motion of the occupant during a collision. The deployment of the airbag and the utilization of the seat belt mechanisms decrease the likelihood of serious injury for the occupants.
If vehicle occupants are positioned too close to the airbag or if a child seat is buckled to the seat, it may be desirable to vary the inflation and deflation rates of the airbag or to prohibit deployment of the airbag to prevent injury to the occupant from the impact of the airbag. It may also be desirable to control the seat belt pretensioner and retractor mechanisms to further prevent injury to occupants.
Occupant sensing systems are used to provide information to optimize or suppress deployment of an airbag if an occupant is determined to be too close to the airbag. These systems typically use a single input to a controller to determine whether or not the airbag should be deployed. The input is usually based on measurement of the seat occupant""s weight or monitoring of the occupant""s position relative to the airbag deployment area. Based on this input, the controller sends an output signal to control airbag inflation or deflation if a collision occurs.
These systems often do not consider other important factors such as child seat usage, seat belt usage, pre-crash vehicle data, crash severity data, braking data, etc. in determining whether or not to deploy the airbag. Further these systems do not utilize multiple outputs to control both the airbag deployment and the seat belt mechanisms to minimize injury to the occupants.
Thus, it is desirable to have an occupant restraint control system that can utilize multiple inputs to provide multiple output signals to optimize deployment of the occupant restraint system including the operation of seat belt pretensioner and retractor mechanisms and the inflation/deflation rates of the airbag. The system should be easy to install and maintain and should also be easily adaptable to any combination of sensors.
An occupant restraint system includes a plurality of sensors that provide multiple input signals to a processing unit. The processing unit has a fuzzy logic control system that processes the multiple input signals to generate multiple output signals to optimize deployment of the occupant restraint system. The occupant restraint system preferably includes an airbag assembly with an airbag controller for inflating and deflating an airbag and a seat belt assembly having a seat belt pretensioner mechanism and a seat belt retractor mechanism for controlling the movement of an occupant during a collision.
In one disclosed embodiment, the occupant restraint system includes at least one modifier sensor for generating a modifier signal to enable or disable an occupant restraint system, an occupant sensor assembly for generating an occupant signal representing multiple occupant characteristics, and a collision sensor assembly for generating a collision signal representing vehicle collision characteristics. The processing unit receives the input signals including the modifier, occupant, and collision signals and generates at least one output signal based on the input signals that optimizes deployment of the occupant restraint system.
In a preferred embodiment, the at least one modifier sensor can include various combinations of the following sensors: an occupant presence sensor for determining whether an occupant is present within a predetermined area within the vehicle; a child seat sensor for determining whether a child seat is properly positioned within the predetermined area; and a seat belt usage sensor for determining whether a seat belt harness is being utilized by the occupant. The occupant presence sensor generates an occupant signal that is positive when the occupant is in the predetermined area and negative when the occupant is not in the predetermined area. The child seat sensor generates a child seat signal that is positive when the child seat is properly positioned within the predetermined area and negative when the child seat is not present or improperly positioned within the predetermined area. The seat belt usage sensor generates a seat belt signal that is positive when the seat belt harness is in an engaged position and negative when the seat belt harness is in a disengaged position. The modifier signal is compiled from the combination of the occupant presence, child seat, and seat belt signals.
In a further preferred embodiment, the occupant sensor assembly includes a weight sensor for generating a weight signal representing occupant weight and an occupant proximity sensor for generating an occupant proximity signal representing occupant position relative to a deployment area for the occupant restraint system. The occupant signal is compiled from the combination of the weight and proximity signals. Additionally, the collision sensor assembly includes a severity sensor for generating a severity signal representing collision characteristics occurring at the time of or just after collision and a pre-collision sensor for generating a pre-collision signal representing vehicle characteristics occurring just before collision. The collision signal is compiled from the combination of the severity and pre-collision signals.
Thus, the input to the processing unit is comprised of a plurality of input signals including the modifier signal comprised of an occupant presence signal, a child seat signal, and a seat belt usage signal, the occupant signal comprised of an occupant weight signal and an occupant proximity signal, and the collision signal comprised of a collision severity signal and a pre-collision signal. In the preferred embodiment, the at least one output signal is comprised of a plurality of output signals. These output signals can be any of various combinations of the following signals: a multi-stage inflation control signal for controlling the profile of the airbag; a variable venting control signal for controlling deflation speed of the airbag; and a retractor control signal for controlling the retraction force of the seat belt retractor mechanism. Further, the processing unit preferably includes a fuzzy logic control system for optimizing the plurality of output signals based on the plurality of input signals.
A method for controlling an occupant restraint system includes the following steps. At least one modifier signal is generated which can enable or disable an occupant restraint system based on satisfaction of a predetermined condition. An occupant signal is generated that represents multiple occupant characteristics and a collision signal is generated that represents vehicle collision characteristics. The modifier, occupant, and collision signals are transmitted as multiple input signals to a processing unit and at least one output signal is generated based on the input signals to optimize deployment of the occupant resraint system.
One advantage of this system is that multiple inputs are used to specifically tailor multiple outputs for controlling the occupant restraint system. All of the inputs are combined and are necessary to produce the required outputs. The application of a fuzzy logic control system to all of these independent and variable inputs produces the proper control signals for the airbag and seat belt restraint systems while optimizing the total system response in real time. As a result, the tailored response of the occupant restraint system will have adapted to vehicle conditions sensed prior to and during the collision.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.